In his latest, Andrei Zmievski talks a bit about an article over on the Ohloh.net website (statistics site that analyzes the source of Open Source applications) titled "PHP Eats Rails for Breakfast".
So far they've indexed over 3,000 projects and their conclusion seems to be that among Web scripting languages, PHP is the undisputed champion (as measured by the LOC count).
He also notes that they've discovered something interesting - despite the lowering numbers of developers/projects being done with PHP, the code and applications seem to be growing still. Andrei interprets this as a positive move for developers away from the "reinvent the wheel" school of thought to a more "find something that works already and go from there".
Check out the original article for more information on the stats and some charts to show the trends.